It may cause by the network traffic, please wait for 5 mins and then try it again.

And please check following steps:

1. Make sure the signal is good and your phone working normally, please find a place where provide a good signal condition if your signal is not stable.

2. Shut down your moblie functions such as firewall, auto-block or blacklist

3. Restar your mobile phone.

Please contact official team and send us your phone model and system (Android, iOS) and provide your location, we will help you as soon as possible if your still cannot receive SMS code after restart many times.